Global communications traffic in the form of voice, data, and video has grown tremendously in the past decade. To meet demand, communications bandwidth capacity and geographic coverage have been substantially expanded. Optical signals sent over optical fiber have been a key factor in enabling these advances.
A growing number of communications carriers are deploying optical switches, that is, switches that steer light pulses among different fiber spans without converting them into electrical signals at any point. The advantages of all-optical switching are significant. Optical switches promise to relieve bottlenecks, reduce costs, and provide good scalability.
Researchers are at work on various technologies for optical switching. These include the use of tiny micro-mirrors, liquid crystals, bubbles, holograms, and thermo- and acousto-optics. It may be that different of these technologies are suitable for different applications. For example, some switching fabrics may be better for large scale applications such as optical cross connects, whereas other technologies may be more appropriate for optical add-drop multiplexers or gear used in metro as opposed to long haul networks.